Re: [PATCH v13 2/6] usb: dwc3: core: Host wake up support from system suspend

[Pavan Kondeti]

Hi Sandeep,

On Tue, Apr 12, 2022 at 12:08:02PM +0530, Sandeep Maheswaram (Temp) wrote:
> Hi Pavan,
> 
> On 4/12/2022 10:30 AM, Pavan Kondeti wrote:
> >Hi Sandeep,
> >
> >On Tue, Apr 12, 2022 at 10:16:39AM +0530, Sandeep Maheswaram (Temp) wrote:
> >>Hi Matthias,
> >>
> >>On 4/12/2022 2:24 AM, Matthias Kaehlcke wrote:
> >>>On Tue, Apr 12, 2022 at 12:46:50AM +0530, Sandeep Maheswaram wrote:
> >>>>During suspend read the status of all port and set hs phy mode
> >>>>based on current speed. Use this hs phy mode to configure wakeup
> >>>>interrupts in qcom glue driver.
> >>>>
> >>>>Check wakep-source property for dwc3 core node to set the
> >>>s/wakep/wakeup/
> >>Okay. Will update in next version.
> >>>>wakeup capability. Drop the device_init_wakeup call from
> >>>>runtime suspend and resume.
> >>>>
> >>>>Also check during suspend if any wakeup capable devices are
> >>>>connected to the controller (directly or through hubs), if there
> >>>>are none set a flag to indicate that the PHY is powered
> >>>>down during suspend.
> >>>>
> >>>>Signed-off-by: Sandeep Maheswaram <quic_c_sanm@xxxxxxxxxxx>
> >>>>---
> >>>A per-patch change log would be really helpful for reviewers, even
> >>>if it doesn't include older versions.
> >>Okay. Will update in next version.
> >>>>  drivers/usb/dwc3/core.c | 33 ++++++++++++++++++++-------------
> >>>>  drivers/usb/dwc3/core.h |  4 ++++
> >>>>  drivers/usb/dwc3/host.c | 25 +++++++++++++++++++++++++
> >>>>  3 files changed, 49 insertions(+), 13 deletions(-)
> >>>>
> >>>>diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> >>>>index 1170b80..effaa43 100644
> >>>>--- a/drivers/usb/dwc3/core.c
> >>>>+++ b/drivers/usb/dwc3/core.c
> >>>>@@ -32,6 +32,7 @@
> >>>>  #include <linux/usb/gadget.h>
> >>>>  #include <linux/usb/of.h>
> >>>>  #include <linux/usb/otg.h>
> >>>>+#include <linux/usb/hcd.h>
> >>>>  #include "core.h"
> >>>>  #include "gadget.h"
> >>>>@@ -1723,6 +1724,7 @@ static int dwc3_probe(struct platform_device *pdev)
> >>>>  	platform_set_drvdata(pdev, dwc);
> >>>>  	dwc3_cache_hwparams(dwc);
> >>>>+	device_init_wakeup(&pdev->dev, of_property_read_bool(dev->of_node, "wakeup-source"));
> >>>>  	spin_lock_init(&dwc->lock);
> >>>>  	mutex_init(&dwc->mutex);
> >>>>@@ -1865,6 +1867,7 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
> >>>>  {
> >>>>  	unsigned long	flags;
> >>>>  	u32 reg;
> >>>>+	struct usb_hcd  *hcd = platform_get_drvdata(dwc->xhci);
> >>>>  	switch (dwc->current_dr_role) {
> >>>>  	case DWC3_GCTL_PRTCAP_DEVICE:
> >>>>@@ -1877,10 +1880,7 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
> >>>>  		dwc3_core_exit(dwc);
> >>>>  		break;
> >>>>  	case DWC3_GCTL_PRTCAP_HOST:
> >>>>-		if (!PMSG_IS_AUTO(msg)) {
> >>>>-			dwc3_core_exit(dwc);
> >>>>-			break;
> >>>>-		}
> >>>>+		dwc3_check_phy_speed_mode(dwc);
> >>>>  		/* Let controller to suspend HSPHY before PHY driver suspends */
> >>>>  		if (dwc->dis_u2_susphy_quirk ||
> >>>>@@ -1896,6 +1896,16 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
> >>>>  		phy_pm_runtime_put_sync(dwc->usb2_generic_phy);
> >>>>  		phy_pm_runtime_put_sync(dwc->usb3_generic_phy);
> >>>>+
> >>>>+		if (!PMSG_IS_AUTO(msg)) {
> >>>>+			if (device_may_wakeup(dwc->dev) &&
> >>>>+			    usb_wakeup_enabled_descendants(hcd->self.root_hub)) {
> >>>You did not answer my question on v12, reposting it:
> >>>
> >>>   Did you ever try whether you could use device_children_wakeup_capable() from
> >>>   [1] instead of usb_wakeup_enabled_descendants()?
> >>>
> >>>   [1] https://patchwork.kernel.org/project/linux-usb/patch/1635753224-23975-2-git-send-email-quic_c_sanm@xxxxxxxxxxx/#24566065
> >>Sorry ..I have replied in mail yesterday but it is not showing up in
> >>patchwork link.
> >>
> >>Tried with  device_children_wakeup_capable(dwc->dev) instead of
> >>usb_wakeup_enabled_descendants and it always returns true even
> >>
> >>when no devices are connected.
> >>
> >What do you mean by when no devices are connected? There is always
> >root hub connected and we should not power down the DWC3 here even
> >when remote wakeup for root hub is enabled. Essentially
> >usb_wakeup_enabled_descendants() returns true even without any
> >physical devices connected.
> >
> >What does device_children_wakeup_capable() do? Sorry, I could not
> >find this function definition.
> >
> >Thanks,
> >Pavan
> 
> usb_wakeup_enabled_descendants() doesn't consider hubs. It only returns true if any devices
> are connected with wakeup capability apart from hubs. If we consider hubs also dwc3 core exit
> and phy exit will never be called.
> 

copy/pasting the code here. you are passing roothub as udev. As you can see
this function clearly takes the remote wakeup of root hub into account. Lets
take a simple case, we have a roothub with one port. nothing attached. so
we enter runtime suspend. Don't you want to keep PHY ON? otherwise, how can
you detect if a keyboard/mouse attached directly to root hub? 

In your configuration, is remote wakeup enabled for the roothub or not?

/* Count of wakeup-enabled devices at or below udev */
unsigned usb_wakeup_enabled_descendants(struct usb_device *udev)
{
	struct usb_hub *hub = usb_hub_to_struct_hub(udev);

	return udev->do_remote_wakeup +
			(hub ? hub->wakeup_enabled_descendants : 0);
}
> device_children_wakeup_capable() implementation was shared by Matthias in below thread
> https://patchwork.kernel.org/project/linux-usb/patch/1635753224-23975-2-git-send-email-quic_c_sanm@xxxxxxxxxxx/#24566065
> 
> Probably device_children_wakeup_capable() is returning true because it considers hubs also.
> 

if you see choose_wakeup(), it derives the USB remote wakeup capability from
the device_may_wakeup(), so the patch suggested might work. Note that we have
to take wakeup capability of roothub into account even when there is no
USB device attached.

Thanks,
Pavan